Typical prior art devices are illustrated in U.S. Pat. Nos. 3,791,583 and 4,082,057. These two patents disclose cleaning apparatuses which are provided with a spray means which is retracted into a housing attached to a vessel when not in use. Typically these devices are operated by a hydraulic system which is relatively expensive to manufacture, install, repair and maintain. Additionally, with regard to such devices it is important that the spray means be properly positioned within the vessel. Because of this positioning, prior art devices use extension arms which are relatively long in length, usually at least as long as the distance it must extend into the vessel. Further in the some prior art devices, the fluid which provides wash head pressure is also used to provide pressure to the hydraulic system. Generally these devices are designed to be used with head pressures of 150 psi or higher. A head pressure of 1000 psi or higher may be used in some applications. As the pressure increases the strength and weight of prior art devices must necessarily increase to accommodate this increased pressure. This obviously results in an increase in cost to manufacturer.
Additionally in certain prior art devices, of example as illustrated in U.S. Pat. No. 4,082,057, an isolation valve is used to separate the cleaning apparatus from the vessel when not in use. Since some cleaning apparatus are about 12 inches in diameter, an isolation valve of 16 inches would be necessary. Such a valve could weigh as much as 1 ton and would be expensive to manufacture.
In some situations, the amount of space adjacent the vessel is limited, thereby making it virtually impossible to position the apparatus without substantial expense in modifying the surrounding site.
Another disadvantage of prior art devices is that they cannot be removed from the vessel without exposing the interior to atmosphere nor are they designed for easy use with multiple vessels.
Applicants have invented an improved cleaning apparatus that is simple in operation, reliable in performance, provides easy access for repair, relatively lightweight in construction and less expensive to manufacture. There is also provided means for easy removal of the apparatus without exposing the contents of the vessel and would permit use of the apparatus with multiple vessels. Additionally, there is provided means to extend the spray means into the vessel with a minimum amount of overall length to the apparatus.